Generally, a stabilizer for turning on a high-voltage discharge lamp has a structure in which a copper wire is wound around a silicon steel sheet. The lamp has great power dissipation of the silicon steel sheet core and the copper wire because it uses a frequency of 50 or 60 Hz. In addition, the lamp has great weight and volume, which makes it difficult to dispose and treat.
To solve these problems, several types of electronic stabilizers using semiconductor have been recently developed. All such stabilizers, however, may cause electromagnetic interference with peripheral devices or electric shock accident.
A related art stabilizer circuit for a high-voltage discharge lamp to solve such problems is shown in FIG. 1. Referring to FIG. 1, a buck converter 10 includes a transistor TR1, a Zener diode Z1, capacitors C6 and C7, diodes D1, D2 and D3, a voltage control logic IC2, and a transformer L1.
The buck converter 10 converts a 380V DC voltage to an AC voltage, boosts the AC voltage, and converts the boosted AC voltage to a DC voltage. The system reference voltage generator 12 includes resistors R23, R24 and R25 and a Zener diode Z3. The system reference voltage generator 12 generates a set reference voltage Vref.
A commutator 14 includes a pulse width modulation controller IC3, capacitors C13, C14, C15 and C16, resistors R26 and R27, and transistors TR2, TR3, TR4 and TR5. The commutator 14 receives the converted DC voltage from the buck converter 10 and controls to supply constant current to an igniter 16. The igniter 16 includes a capacitor C2, a diode D2, a coil L2, a transformer L3, Zener diodes Z4, Z5, Z6 and Z7. The igniter 16 receives the voltage from the commutator 14 and generates a high voltage to apply the high voltage to a high-voltage discharge lamp 18.
The high-voltage discharge lamp 18 is turned on by the high voltage generated by the igniter 16. A current detector 20 detects an amount of current using resistors R1, R2 and R3 when the high voltage is fed back from the igniter 16. A voltage detector 22 detects the voltage outputted from the buck converter 10 using resistors R6 and R7.
A watchdog timer 24 includes resistors R12, R13, R14, and R15, capacitors C5 and C8, a transistor TR6, and an operational amplifier OP1. The watchdog timer 24 compares the detected voltage with the reference voltage generated by the reference voltage generator 12 and outputs a pulse for sensing abnormality in the high voltage at set time intervals.
A current and voltage error sensor 26 includes resistors R4, R5, R10, R11, R17, R18 and R19, capacitors C9, C10 and C11, a Zener diode Z2, and a voltage and current control logic IC1. The current and voltage error sensor 26 receives the current value detected by the current detector 20, the voltage value detected by the voltage detector 22 and the pulse signal output from the watchdog timer 24 to sense voltage and current error states.
An igniter voltage controller 28 includes resistors R20, R21 and R22, a capacitor C12, and an operational amplifier OP2. The igniter voltage controller 28 controls the application of a constant voltage to the igniter 16. The conventional stabilizer circuit for the high-voltage discharge lamp described above is available in capacity of 70 to 140 W. However, in high capacity exceeding for example 250 W, current increases, damaging the voltage control logic IC2 of the buck converter 10.